1. Field of the Invention
The present invention relates to the field of linear accelerators utilizing focusing fields. More specifically, it relates to multi-pass and energy-recovering linear accelerators and improved focusing methods therefor.
2. Description of the Prior Art
Linear accelerators are generally well known in the prior art. Fundamentally, a linear accelerator works by utilizing radio-frequency (RF) energy to accelerate charged particles. The charged particles may be electrons, protons, ions, or any of various particles, which may be capable of holding a charge.
RF energy is applied to the charged particles by at least one and usually a series of drift tubes, which vary in length and in other dimension and characteristics according to such design variables as the speed or size of the particle, the charge on the particle, the RF energy applied (wavelength and intensity), and focusing effects. As the drift tubes increase in number, a pronounced spreading effect is observed in the particle beam if left uncorrected.
This spreading effect has been long known and is countered in numerous ways in the known prior art. The primary ways of counteracting the drift effect may be divided into two main categoriesxe2x80x94electrostatic and electromagnetic.
Most linear accelerators are designed to accept particles at a so-called design injection velocity and in preordained xe2x80x9cbunchesxe2x80x9d. Other design limitations include losses from beam mismatch, and excessive gaps between the drift tubes, which can cause particle dispersion.
One of the most troublesome problems to address in the array of design considerations is the matching of the various energies to tube length, RF, and gap to provide for the fewest losses and consequently the most efficient particle accelerator.
Thus, it is an object of the present invention to provide a multi-pass or energy recovering linac with a more closely matched energy profile through the accelerator.
It is another object of the present invention to provide a more efficient linac, which is capable of receiving a wide range of input energy-level particles.
These, and other objects, will become readily apparent to one of skill in the art having regard for this disclosure.
The present invention provides an improvement in the beam dynamic control, beam confinement, beam stability, and an increased allowable dynamic range of injected to final energy. This is accomplished by the inventive novel beam transport topology and focusing methodologies.